Warning: require(vendor/autoload.php): failed to open stream: No such file or directory in /home/pruebast/public_html/phpmailer/get_oauth_token.php on line 18

Fatal error: require(): Failed opening required 'vendor/autoload.php' (include_path='.:/usr/share/php') in /home/pruebast/public_html/phpmailer/get_oauth_token.php on line 18